HD650 Dynamat Mods - Proof That It's Not BS! So far, those of us who have done the standard measurements have found no conclusive proof via measurements that the Dynamat Extreme mods even do anything, and that this mod could be placebo. @CEE TEE gave me his HD650 and asked to perform the final touches of the HD650 M mods. He mentioned it didn't sound right, that his didn't sound like mine with the full mods. I wasn't too sure myself about the Dynamat Extreme mods, so I took this opportunity to take another look. This time with some different kinds of measurements. Note that "stock" does not denote stock, but with the quarter mod and foam removal mod already implemented. "Modded" means the addition of the Dynamat Extreme to the quarter/foam modded headphone. Full Spectrum, 1kHz Tone. Top = Stock, Bottom = Modded Note lower noise floor in the bass? Could this be attributed to better environmental conditions when the modded HD650 measurements were taken? Let's explore more. Full Spectrum, 75Hz Tone. Top = Stock, Bottom = Modded Note lower noise floor in the sub and low bass region. Also note lower 4th and 5th order distortion and slightly lower 3rd order. Full Spectrum, 50Hz Tone. Top = Stock, Bottom = Modded Again, note lower noise floor in the sub and low bass region. Just cleaner all around the 50Hz tone. Also note lower distortion from 3rd order on.